If you're in the process of leveling a new character in World of Warcraft, heirloom armor and weapons can help enhance your leveling experience in more ways than one. The stats in heirlooms will scale with your level, and possibly provide bonus experience for killing monsters and completing quests. For an added power boost, you can even enchant your heirlooms.
Level 1-80 Heirlooms
These can be purchased from the Justice Points vendor in your faction's capital city. You can also purchase them using Champion's Seals at the Argent Tournament Grounds.
Chest: 10% bonus XP
Shoulders: 10% bonus XP
Weapons: No XP bonus
Trinkets: No XP bonus
Level 1-85 Heirlooms
These are purchased from the Guild Vendor at the welcome center in your faction's capital city. You need to be at least honored with your guild in order to purchase them.
Cloak: 5% bonus XP (Requires guild level 10)
Helm: 5% bonus XP (Requires guild level 20)
Enchanting Your Heirlooms
Heirloom items are considered to be item level 1, and therefore any enchant with a minimum item level requirement cannot be used. High-level vanilla enchants will be the only way to go for enchanting your heirlooms.
Power Level With More XP Bonuses
With all four XP-bonus-giving heirlooms equipped, you'll be receiving 30% bonus XP on your new character. This is in addition to guild perks, and refer-a-friend bonuses. Add them all up and you'll be level 85 in no time!